3.4 Overload and power factor

In this simulation, an R-L load of 0.7 power factor is connected. Initially, the load operates with a value of 500 kVA; then at t ¼ 0:10 s, the load increases to 1000 kVA.

Under these conditions, it must be verified that the power factor at the input is approximately 1 and that the output voltage maintains its nominal value. Figure 12

Figure 10. Harmonic waveform behavior: (a) load current and (b) grid current.

Figure 11. Harmonic power behavior at the SST (a) input and (b) output.

Figure 12.

Overload waveform behavior: (a) grid voltage, (b) load voltage, (c) grid current, and (d) load current.

Figure 13. Overload power behavior at the (a) grid side and (b) load side.

Figure 14. Power factor behavior at the (a) grid side and (b) load side.

presents an increment in the magnitude voltage and a decrement in the current load; consequently the active and reactive power behavior is as given in Figure 13. The power factor in the load side does not affect the power factor at the input side (grid), as shown in Figure 14. It is verified that the SST can operate normally with an overload of 125%, and the power factor improves.

Initially, a load of 50% of their nominal demand is connected; later the load increases to 100% with a power factor of 0.85 lagging, as shown in Figure 16(c). It is observed that at t ¼ 0:07 s, the distributed generation starts to deliver active

(a) Generator active and reactive power, (b) generator power factor, (c) R-L load power factor, (d) power factor of the distributed energy source, and (e) power of the distributed energy source and the storage energy.

Figure 15.

Figure 16.

133

Electrical diagram for a bi-directional power flow.

Solid-State Transformer for Energy Efficiency Enhancement

DOI: http://dx.doi.org/10.5772/intechopen.84345

power, as shown in Figure 16(d). Then the input power coming from the grid decreases until reaching a negative value as presented in Figure 16(a); this means that the distributed generation is delivering power to the load and the grid. Then at
